What’s Vulnerable › Vulnerabilities

CVE-2026-55191: FreeRDP: Heap-buffer-overflow write in AVC444 YUV buffer allocation

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-08-19 · updated 2026-10-26
• Weakness: CWE-122

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients that negotiate RDPGFX AVC444 with an H.264 decoder backend calculate the intermediate YUV444 allocation size in libfreerdp/codec/h264.c with 32-bit multiplication in avc444_ensure_buffer. A malicious RDP server can supply surface dimensions for which piDstStride multiplied by padDstHeight wraps to a small nonzero value, causing winpr_aligned_recalloc to allocate an undersized buffer before YUV420CombineToYUV444 writes using the actual stride and rectangle dimensions. This can cause a client crash and may permit code execution through attacker-influenced heap corruption. This issue is fixed in version 3.27.0.

Affected products

• FreeRDP: before 3.27.0 — fixed in 3.27.0

How to fix

Upgrade to a fixed version: FreeRDP 3.27.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/commit/97f40b9e766af375f4e41ac6a3f4397d708d249c
• https://github.com/FreeRDP/FreeRDP/pull/12873
• https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr

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